External and internal cathodic protection of storage oil tanks

"The aim of this paper is to develop the cathodic protection system (CPS) for the internal and external face of a 2500 cubic meters (m3) crude oil storage tank in order to prevent its body from corrosion and keep its integrity. External cathodic protection is done by 99.98 % Zinc (Zn) galvanic anodes while internal cathodic protection is achieved by 6.5 % Aluminum-Zinc (Al-Zn) galvanic anodes. A case study of an oil tank from the Romanian refinary field is taken to do the CPS. The total number of anodes required to protect the oil tank externally and internally are 20 and 123 anodes respectively. A sensitivity analysis study was done utilizing ANODEFLEX 1500 software in order to investigate the effect of changing the depth of anode place under the tank bottom. It was found that the deeper anode depth is, the longer anode spacing is along the total area of tank bottom. "